The invention relates to an apparatus for clamping and/or longitudinally moving an elongate traction means, such as a wire rope or rod or other tension bearing linear body relative to a casing or frame of a lifting apparatus or the like. The apparatus comprises at least one first clamping jaw and at least one second clamping jaw provided on mutually opposite sides of a linear body and adapted to be moved in relation to one another transversely to the longitudinal direction of the linear body with the aid of at least one clamping lever. The clamping lever acts on a clamping key mechanism finding support against both clamping jaws and being rotatable in at least one clamping jaw.